Hip distraction

ABSTRACT

A hip distractor includes a pair of distractor members and a support configured to be fastened to a surgical table. The support includes at least two mounts for coupling to a pair of joints that couple the distractor members to the support. Another hip distractor includes a pair of distractor assemblies that are configured to apply a distraction load to a patient. Each of the assemblies includes a joint for coupling the corresponding assembly to a surgical table. The joint permits vertical and horizontal angular adjustment of the corresponding assembly. A method of distracting a hip includes coupling a patient&#39;s legs to a pair of distractor assemblies and simultaneously adjusting a vertical angle and a horizontal angle of at least one of the distractor assemblies.

TECHNICAL FIELD

This invention relates to hip distraction.

BACKGROUND

To gain access to the hip joint to perform, e.g., hip arthroscopy,orthopedic hip pinning or minimally-invasive hip joint replacement, thefemoral head (ball) is pulled out of the acetabulum (socket) in thepelvis. Hospitals typically use a fracture table to put the hip jointunder traction while the patient is in a supine position. Hipdistractors are known that attach to a standard operating table, andthat are dedicated to use with the patient in either a supine positionor a lateral position.

Two methods for hip distraction are Distraction Mode, in which the lowerextremity is put in tension via traction between the foot and pelvis,and Femoral Acetabular Impingement (FAI) Mode, in which there is notraction on the lower extremity and there is a larger range of motionthan the distraction mode. In the FAI Mode, the hip is flexed up between30 to 90 degrees and the knee is flexed approximately 45 degrees. Thescrub nurse holds the knee from falling laterally. Both methods can beperformed using a fracture table with the patient in the supineposition. To move a patient between the two modes, and to move the hipjoint through its range of motion to check for impingement between thefemoral neck and the acetabular rim, the circulator nurse reaches underthe draped foot area to unlock the table.

SUMMARY

According to one aspect, an apparatus includes a distractor assemblyadapted to couple to a leg and capable of providing a distraction loadon the leg in both supine and lateral positions of the leg.

Embodiments of this aspect may include one or more of the followingfeatures. The distractor assembly includes a joint, for example, a balljoint or universal joint, configured to couple the distractor assemblyto a surgical table. The joint is lockable and the mechanism for lockingthe joint is located remote from the joint. The apparatus is configuredsuch that with a patient positioned on the surgical table and coupled tothe distractor, the joint is offset from the patient's hip joint. Theapparatus is entirely supported by a surgical table.

In an illustrated embodiment, the distractor assembly includes adistractor member and a leg mount, for example, a foot mount, coupled tothe distractor member for movement relative to the distractor member byboth sliding and threaded engagement. The leg mount is coupled to thedistractor member by a ball joint. The apparatus includes a foot holdermountable to the distractor assembly and including a support bar thatsupports the lower leg in the lateral and supine positions.

The apparatus further includes a support configured to be fastened to asurgical table, and the distractor assembly includes a joint, forexample, a ball joint or a universal joint, coupling the assembly to thesupport. The support includes two mounts for coupling to the joint andthe distractor assembly is arranged for use with a patient in a supineposition with the joint coupled to a first of the mounts for surgery ona right leg, or to a second of the mounts for surgery on the left leg.

According to another aspect, a method includes coupling a leg to adistractor assembly, positioning the leg in one of a distraction modeand a femoral acetabular impingement mode, and repositioning the leg inthe other of the modes without the need for accessing a drapedpelvis/thigh region.

According to another aspect, an apparatus includes a distractor memberconfigured for coupling to patient table, and a leg mount coupled to thedistractor for movement relative to the table by both sliding andthreaded engagement.

According to another aspect, an apparatus includes a distractor memberconfigured for coupling to patient table, a ball joint, and a leg mountcoupled to the distractor member by the ball joint. The apparatus isconfigured such that relative movement between the foot mount and thetable applies a distraction load to a patient. Embodiments of thisaspect may include that the apparatus is configured to be entirelysupported by a surgical table.

According to another aspect, an apparatus includes a distractor assemblyconfigured to apply a distraction load to a patient including a balljoint or a universal joint for coupling the assembly to a surgicaltable.

Embodiments of this aspect may include that the joint is lockable, andthat the apparatus is configured such that with a patient positioned onthe surgical table and coupled to the distractor assembly, the joint isoffset from the patient's hip joint.

According to another aspect, an apparatus includes a foot holder for useduring surgery having a support bar configured and arranged to support apatient's lower leg.

According to another aspect, an apparatus includes a distractor member,a support configured to be fastened to a surgical table, and a jointcoupling the distractor member to the support. The support includes atleast two mounts for coupling to the joint.

According to another aspect, a method includes coupling a distractormember to a patient's leg, and dislocating the patient's hip by applyingan adduction force to the patient's leg.

According to another aspect, a method includes coupling a distractormember to a patient's leg, and applying a distraction force with thedistractor member to the patient's leg through a bent knee.

According to another aspect, an apparatus includes means for providing adistraction load on a leg in both supine and lateral positions of theleg.

According to another aspect, an apparatus includes means forrepositioning a leg between a distraction mode and a femoral acetabularimpingement mode without the need for accessing draped pelvis/thighregion.

According to another aspect, an apparatus includes a pair of distractormembers, a support configured to be fastened to a surgical table, and apair of joints for coupling the distractor members to the support. Thesupport includes at least two mounts for coupling to the joints.

Implementations of this aspect may include one or more of the followingfeatures. For example, the apparatus includes a forked post including apair of support posts and a center post. The forked post includes aperineal pad supported by the center post. The support includes a pairof through holes, each support post being received in one of the holes.The support includes a pair of external plugs, each support post beingreceived over one of the plugs. A leg mount is coupled to one of thedistractor members for movement relative to the one of the distractormembers by both sliding and threaded engagement. A second leg mount iscoupled to other of the distractor members for movement relative to theother of the distractor members by both sliding and threaded engagement.The apparatus includes a mechanism for locking one of the joints. Thejoint is lockable. An actuator for the mechanism is located remote fromthe joint. The apparatus is configured to be entirely supported by thesurgical table.

According to another aspect, an apparatus includes a pair of distractorassemblies configured to apply a distraction load to a patient. Each ofthe assemblies includes a joint for coupling the corresponding assemblyto a surgical table. The joint permits vertical and horizontal angularadjustment of the corresponding assembly.

Implementation of this aspect may include one or more of the followingfeatures. For example, each joint permits vertical angular adjustment ofgreater than about twenty degrees from horizontal, and a total range ofhorizontal angular adjustment of greater than about twenty degrees. Eachjoint permits vertical angular adjustment of greater than aboutforty-five degrees from horizontal, and a total range of horizontalangular adjustment of greater than about forty-five degrees. At leastone of the joints is a ball joint. At least one of the joints is auniversal joint. The apparatus is configured to be entirely supported bythe surgical table.

According to another aspect, a method includes coupling a patient's legsto a pair of distractor assemblies and simultaneously adjusting avertical angle and a horizontal angle of at least one of the distractorassemblies.

Implementations of this aspect may include one or more of the followingfeatures. For example, adjusting the vertical angle includes rotatingthe distractor assembly greater than about twenty degrees fromhorizontal. Adjusting the horizontal angle includes rotating thedistractor assembly greater than about twenty degrees. The methodincludes fastening a support to a surgical table to support the pair ofdistractor assemblies. The method includes remotely locking the verticalangle and the horizontal angle of at least one of the distractorassemblies.

According to another aspect, a device includes a forked post including aconnector plate having a first side and a second side, a center postextending from the first side of the connector plate, and a pair ofsupport posts extending from the second side of the connector plate. Thecenter post is equidistant from each of the support posts. The devicealso includes a platform configured for attachment to a surgical tableand defining a pair of holes spaced to receive the support posts.

Implementations of this aspect may include one or more of the followingfeatures. For example, the device includes a perineal pad supported bythe center post. The forked post is configured to support the perinealpad in a substantially transversely centered location of the platform.

According to another aspect, a method of performing a procedure includespositioning a forked post on a support fastened to a surgical table. Theforked post includes a connector plate having a first side and a secondside, a center post extending from the first side of the connectorplate, and a pair of support posts extending from the second side of theconnector plate. The center post is equidistant from each of the supportposts. The method also includes positioning a patient on the surgicaltable such that the center post is between the patient's legs.Implementations of this aspect may include, for example, passing each ofthe support posts through one of a pair of through holes in the support.

Advantages of the apparatus and method may include ease of positioningthroughout the large range of motion required in FAI Mode, ease ofrepositioning between Distraction and FAI Modes, a single system thatallows for both supine and lateral positioning, freeing the scrub nursefrom holding the knee from falling laterally in FAI Mode, ease ofpositioning or repositioning both of the patient's legs before andduring procedures, and less expensive than a fracture table.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a distraction assembly arranged for use in aDistraction Mode with the patient in a supine position.

FIG. 2 illustrates the distraction assembly arranged for use in aDistraction Mode with the patient in a lateral position.

FIG. 3 illustrates the distraction assembly arranged for use in a FAIMode with the patient in a supine position.

FIG. 4 illustrates the distraction assembly arranged for use in a FAIMode with the patient in a lateral position.

FIG. 5 is an isometric view of the distraction assembly and a footholder attached to the distraction assembly.

FIG. 6 is an isometric view of a ball joint of the distraction assembly.

FIG. 7 is an isometric view of a slider and foot mount of thedistraction assembly.

FIG. 8 shows the foot holder attached to the slider.

FIG. 9 is an illustration of a boot of the foot holder.

FIGS. 10A and 10B are isometric views of a table extension for mountingthe distraction assembly to an operating room table with the patient ina supine position.

FIG. 11 is a top view of the distraction assembly also illustrating anon-operative leg holder for the supine position.

FIG. 12 is an isometric view of a lateral positioning table extensionand pad.

FIG. 13 is a top view of the distraction assembly arranged for lateralpositioning.

FIG. 14 illustrates an alternative embodiment of a hip distractor.

FIG. 15 illustrates another alternative embodiment of a hip distractor.

FIG. 16 illustrates a system including a pair of distractor assembliesand a centered perineal pad.

FIG. 17 illustrates a forked post for use with the system of FIG. 16.

DETAILED DESCRIPTION

Hip distraction is performed in either the Distraction Mode (FIGS. 1 and2) or Femoral Acetabular Impingement (FAI) Mode (FIGS. 3 and 4) using asystem 10 that can be attached to a standard operating table 12, such asfound in hospitals and surgery centers, and that can accommodate bothsupine (FIGS. 1 and 3) and lateral (FIGS. 2 and 4) positioning of thepatient. The system 10 permits operating room personnel to repositionthe patient between Distraction Mode and FAI Mode without needing toaccess the draped pelvis/thigh region.

Referring to FIG. 5, a distractor assembly 100 includes a distractionmember, for example, a longitudinal spar 102 having a D-shapedcross-section, a lockable ball joint 104 (available from Allen Medicalof Acton, Mass. and as seen in Allen Medical's Ultrafin stirrupproducts) attached to the proximal (pelvis) end 106 of the spar, acoupler 108 attached to the ball joint 104 for coupling the distractorassembly 100 to an operating room table, a slider 110 slidably mountedon the spar 102, and a leg mount, for example, foot mount 112, attachedto slider 110 via a lockable ball joint 114 and a rigid, stationary arm116. The ball joint 104 can be locked and unlocked by actuating a knob118 located at the distal (foot) end 120 of the spar 102, thus allowingfor the assembly to be unlocked and repositioned without need to accessthe draped pelvis/thigh region.

The ball joint 104 and the coupler 108, as shown in FIG. 6, allows for alarge range of hip motion, providing a full range of motion about thehorizontal axis, and about 80 degrees of motion in the horizontal plane.The coupler 108 includes a yoke 130 that receives horizontally extendingside arms 132 of the ball joint 104.

Referring to FIGS. 5 and 7, the slider 110 defines a D-shapedlongitudinal through bore 150 that slidably and non-rotationallyreceives the spar 102, and a threaded, lateral through a bore 152 thatreceives a locking bolt (not shown), that is tightened to lock theslider 110 to the spar 102. The slider 110 includes handles 154 a, 154 bthat are used by the operating room personnel to slide the sliderrelative to the spar to provide gross distraction of the leg. For finedistraction, the slider 110 includes a base 156 supporting a threadedrod 158 attached to a turn handle 160. The base 156 also slidablysupports a yoke 162 defining a threaded bore 164 through which thethreaded rod 158 is received. By turning the handle 160, the yoke 162,and therefore the foot mount 112 attached to the yoke by the ball joint114 and arm 116, can be moved back and forth relative to the base 156 toapply a desired amount of traction, for example, 25-150 pounds of force,to the leg.

Attached to the foot mount 112 of the assembly 100 is a foot holder 122(FIGS. 5 and 8). The foot holder 122 includes a boot 180 a shin support182, and a support bar 184 that holds the upper tibia aligned with thefoot. The support bar is particularly advantageous during FAI tostabilize the knee from falling laterally thus freeing the scrub nursefrom having to hold the patient's leg in position. Referring also toFIG. 9, boot 180 includes a foot housing 186 with a tightening clasp188, a sole 190, a U-coupling 192 that receives the foot mount 112, andstraps 194 for securing the boot to the foot mount. The foot housing 186has three straps, not shown, that go over the patient's forefoot andclose the foot housing onto the foot.

The support bar 184 has two legs 202 a, 202 b, the ends of which arerespectively received within openings 204 a, 204 b of foot mountcouplers 206 a, 206 b (FIG. 7). The shin support 182 is attached tosupport bar 184 via shin mounts 208. The ball joint 114 and arm 116permit the patient's leg to be finely positioned.

To support the patient's buttocks when the patient is in a supineposition and to attach the distractor assembly 100 to the operating roomtable, a table extension 220 (FIGS. 1 and 10A) is employed. The tableextension 220 includes a frame 222 with a cross bar 224, an angled strut226, a Y-yoke 228, a vertical strut 230, and a platform 232. Extendingfrom the cross bar 224 are two arms 234 a, 234 b that are used to attachthe table extension to the operating room table 12 using rail clamps 14.The coupler 108 of the distractor assembly 100 plugs into one of a pairof female sockets 236 a, 236 b defined in Y-yoke 228 and is secured inplace by a threaded locking knob (not shown). Since the ball joint 104does not provide a large enough range of motion in the horizontal planeto accommodate surgery on both the right and left hip, socket 236 a isused for surgery on the right hip, and socket 236 b is used for surgeryon the left hip, with the ball joint 104 providing the additional rangeof motion in the horizontal plane required for fine position of the leg.

The platform 232 is x-ray translucent and defines through holes 240 a,240 b for receiving a post 242 (FIG. 1). The post 242 is received over arespective plug 244 a, 244 b of Y-yoke 228, and a perineal pad 244(FIG. 1) slips over the post 242. The post and pad provide therestraining force against the pelvis when the distraction force isapplied to the leg. Through hole 240 a is used for surgery on the righthip, and through hole 240 b is used for surgery on the left hip. Asshown in FIG. 10B, a pad 246 is attached to the platform 232. The paddefines a cut-out 248 permitting access to holes 240 a, 240 b.

Referring to FIGS. 10A and 11, a non-operative leg holder assembly 260is secured within the respective opposite socket 236 a, 236 b from thatin which distractor assembly 100 is secured. Assembly 260 includes aspar 262 to which a foot mount 264 is slidably attached via a lockableslider 266 (FIG. 1). Attached to foot mount 264 is a boot 268 throughwhich mild traction, for example, about 20 pounds can be applied to thenon-operative leg.

To position the patient in the supine position for the Distraction Mode(FIG. 1), operating room personnel lower the operating room table's footsection 16 to the vertical position, clamp the table extension 220 tothe side rails 18 of the table, and connect distractor assembly 100 andleg holder 260 to the table extension. A patient transfer board (notshown) can be attached to the table extension to provide interim supportto the legs while the feet are strapped into the boots 180, 268.

The operating room personnel then place the patient on the table,anaesthetize the patient, and attach the perineal post and pad to thetable extension. The patient is then brought down the table firmlyagainst the perineal pad, and the feet are wrapped in disposable foambooties (not shown) and strapped into the boots. The well leg is putunder mild traction and the foot allowed to pivot into it's neutralposition. The operating room personnel remove the patient transfer boardand put the operative leg under initial traction by sliding the slider110 along the spar 102 until mild traction, for example, about 20 to 50pounds, is achieved. The slider 110 is then clamped to the spar. Furthertraction is achieved via the mechanical advantage of the threaded screw158 between the slider 110 and boot 180. This distracts the hip viatraction through the ankle and knee joints. The foot can be locked inany orientation (flexion or rotation) via the ball joint 114 between theboot and the threaded screw.

The surgeon then checks the distraction with fluoroscopy, places a drapeover the patient, including covering the pelvis/thigh region of thepatient, and places portals through the patient's skin leading to thehip joint under fluoroscopy control. As soon as the first portal iscreated the vacuum seal between the femoral head and acetabulum isbroken and the joint distracts further. This can be avoided by injectingfluid into the joint.

To move the patient from Distraction Mode to FAI Mode (FIG. 3), theoperating room personnel reduce the traction force by turning thethreaded screw 158 until no force is on the joint, unlock the ball joint104, and lift the femur into flexion by raising the spar 102. Since thecenter of rotation of the spar, i.e., the ball joint 104, is locatedbelow the hip joint of the patient, the knee flexes as the spar israised. The natural tendency of the knee to fall laterally is limited bythe boot's lateral support bar 202 a, 202 b thus freeing the scrub nurseto help the surgeon.

Referring to FIGS. 12 and 13, for lateral positioning of the patient,the system 10 includes a “U” shaped perineal bar 280 supporting a pad282. The bar 280 has a socket 284 for receiving the coupler 108 (FIG. 5)of the distractor assembly 100, and the pad 282 defines a cut-out 286for accessing socket 284. Bar 280 is attached to the side rails 18 ofthe operating room table 12 using clamps 14.

To position the patient in the lateral position for the Distraction Mode(FIG. 2), with the operating room table's foot section 16 up, theanaesthetized patient is rolled onto their side, the operating roompersonnel clamp the bar 280 to the side rails 18 with the pad 282positioned between the patient'legs. To obtain lateral distraction, theoperating room personnel raise the bar 280 by rotating the bar withinthe clamps 14 and lock the clamps. The distractor assembly 100 is thenattached to the bar 280 and the operative leg wrapped in a disposablefoam bootie (not shown) and strapped into the boot. As discussed above,gross distraction is achieved by moving the slider 110 followed by finedistraction using the threaded screw 158. The boot can be positioned inany combination of flexion or rotation. There is no need for anon-operative leg holder as the non-operative leg is supported by thetable's foot section 16.

To move between the Distraction Mode (FIG. 2) and FAI Mode (FIG. 4), thespar 102 is pivoted laterally along the ball joint 104. Since the centerof rotation of the spar 102, i.e., the ball joint 14, is located distalto the hip joint of the patient, the knee flexes as the spar is movedlaterally. The natural tendency of the knee to fall towards the floor islimited by the boot's lateral support bar 202 a, 202 b, thus freeing thescrub nurse to help the surgeon.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention. Forexample, the distractor assembly can include a tensiometer to providethe surgeon with the distraction force. The slide and spar can be otherthan D-shaped, though preferably the slide and spar are configured suchthat the slide can slide along the spar without rotating. The ball joint104 can be replaced with a two axis universal joint 104 a (FIG. 13).Rather than locating screw thread 158 at slider 110, fine adjustment canbe provided by a screw thread located, for example, between the ball 104and the spar 102.

In an alternative configuration shown in FIG. 14, hip distraction isachieved via a pivoting action. Rather than using only axial force todislocate the hip joint, a lever that pivots along the thigh translate asmall foot adduction (movement towards the body centerline) into a largelateral hip distraction force. With a pivot 301 closer to the hip jointthan to the foot end of a spar 310, a simple lever is created. Theoperative foot is held to the spar 310 by a boot assembly 320. Thus,when a small adduction force F₁ is applied to the spar 310 near the footregion, the mechanical advantage provided by the lever creates a largerlateral force at the hip joint. A perineal pad 344 pushes laterallyagainst the upper femur moving the femoral head of the hip joint. Inaddition to this lateral force, an axial force F₂ is imparted on the hipjoint via traction through the boot assembly 320. This force can beachieved though turning of a crank 360 which is rotationally connectedto a threaded rod 380. The boot assembly 320 is threaded to rod 380 butis limited from rotating by spar 310, thus boot assembly 320 movesaxially when the crank 360 is turned. The perineal pad 344 also providesa reaction force against the pelvis.

Referring to FIG. 15, distraction can be achieved through a bent kneeproviding a more compact distractor. With the operative leg bentapproximately 90 degrees at the knee, the distraction force can beexerted at the knee. In addition, the reactive force that is bornethrough the non-operative leg can be reacted at the knee rather thanthrough the ankle. Bent knee distraction of the operative leg is carriedout by transmitting a distraction force to the upper tibia via a strap430. The distraction force is transmitted through the knee to thefemoral head. A perineal pad 444 is connected to the surgical table andreacts the distraction force by pushing against the pelvis. Atelescoping spar assembly 400 includes a bar 420, which is connected toa tube 410 by a slidable, lockable mechanism, such as a one-wayratcheting pawl.

When distraction is pulled on the operative leg, the pelvis tends torotate around a vertical axis “Z” created by the perineal pad. In orderto minimize this pelvic rotation, a bent knee counter traction force isimparted upon the non-operative leg by a support 440. This force can betransmitted to the upper tibia via surface 450 which is then transmittedthrough the knee to the femoral head and pelvis. The support 440 can befixed to the surgical table or it can telescope like spar assembly 400.If support 440 is fixed then the patient is moved proximally to createthe counter traction force.

Referring to FIG. 16, a system 500 that permits operating room personnelto independently move a patient's legs before and during a procedure,e.g., hip arthroscopy or non-arthroscopic procedures such as orthopedichip pinning and minimally-invasive hip joint replacement, includes twodistractor assemblies 100 a, 100 b, with one replacing leg holderassembly 260 (see FIG. 1). Each distractor assembly 100 a, 100 b is asdiscussed above with respect to distractor assembly 100, and is attachedto the Y-yoke 228 at a respective socket 236 a, 236 b. Although the footholders 122 a, 122 b of the distractor assemblies 100 a, 100 b are notshown with shin supports 182, support bars 184, shin mounts 208 and legs202 a, 202 b (refer to FIG. 8), it is to be understood that these can beattached to each distractor assembly 100 a, 100 b by way of the footmount couplers 206 a, 206 b.

It can be advantageous, e.g., for x-ray and surgical access, to mountthe perineal pad 244 at a centered location on the table extension 220,rather than off-center as shown, for example, in FIGS. 1, 3, and 11.Thus, the system 500 includes a forked post 538 that supports theperineal pad 244 approximately aligned with the transverse center of theoperating table 12. As illustrated in FIG. 17, the forked post 538include two support posts 540 a, 540 b that are fixedly attached to acenter post 542 by way of a connector plate 544. For example, in oneimplementation the center post 542 is located equidistant from each ofthe support posts 540 a, 540 b. Each of the support posts 540 a, 540 bis received in one of the through holes 240 a, 240 b (see FIG. 10A) andover one of the respective plugs 244 a, 244 b of the Y-yoke 228. Theconnector plate 544 rests on the platform 232 of the table extension220. To permit this, a modified pad 546 defines a cut out 548 thatpermits access to both holes 240 a, 240 b at the same time. The perinealpad 244 slips over the center post 542 to provide the restraining forceagainst the patient's pelvis when the distraction force is applied tothe leg.

Accordingly, other embodiments are within the scope of the followingclaims.

1. A device, comprising: a forked post including: a connector platehaving a first side and a second side, a center post extending from thefirst side of the connector plate, and a pair of support posts extendingfrom the second side of the connector plate, the center post beingequidistant from the support posts; and a platform configured forattachment to side rails of a surgical table and defining a pair ofholes spaced to receive the support posts.
 2. The device of claim 1,further comprising a perineal pad supported by the center post.
 3. Thedevice of claim 2, wherein the forked post is configured to support theperineal pad in a substantially transversely centered location of theplatform.
 4. The device of claim 1, wherein the three posts lie in acommon plane.
 5. An apparatus, comprising: a pair of distractor members;a support configured to be fastened to side rails of a surgical table; apair of joints, each joint coupling one of the distractor members to thesupport, wherein the support includes at least two mounts for couplingto the joints; and a forked post including a pair of support posts and acenter post.
 6. The apparatus of claim 5, further comprising a perinealpad supported by the center post.
 7. The apparatus of claim 5, whereinthe support further includes a pair of through holes, each support postbeing received in one of the holes.
 8. The apparatus of claim 5, whereinthe support further includes a pair of external plugs, each support postbeing received over one of the plugs.
 9. A method of performing amedical procedure, comprising: fastening a support to a surgical tableto extend a surface of the table on which a patient lies; positioning aforked post on the support, the forked post including a connector platehaving a first side and a second side, a center post extending from thefirst side of the connector plate, and a pair of support posts extendingfrom the second side of the connector plate, the center post beingequidistant from each of the support posts; and positioning a patient onthe surgical table such that the center post is between the patient'slegs.
 10. The method of claim 9, wherein positioning the forked postincludes passing each of the support posts through one of a pair ofthrough holes in the support.
 11. The method of claim 9, whereinfastening the support includes providing the support with a cushion.